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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6c91cdaf603fdcf2ea150c9b2a77a0ad396ec989e4eeaad30718dbc7896a54e' 
  AND token = 'xOjdV+KYE6pZMiLK/0ZSD7CBtrqdjARPTzgRwlbo36Y=' 
  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"
    }
  }
}