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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0fc21074b15bdf7cc5f0950c46c891076e4017580984200cc8f34ce7a76f95c2' 
  AND token = 'Fbw8QWeUH/SleFS/WqfdQZ+1pnst2bgMZe9bn889YWo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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