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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6d8e9e5581cfdb44021e28b621b4a2d2f9b80e740e1d9fc2d3338a9f2bf5a0d' 
  AND token = 'qN7c3UK8oAYpH37zMkOrTIWJcSRUUZO7M7ItlFOKZeo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}