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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '576750c80e5d2e69287b2273f568c095c38f97aeaa03104b29a6c2d1266bf746' 
  AND token = '6Jw6JMk9yCPLvZw4YYRQuoWl5Z2Wyeb/enH+Ys5ErEA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}