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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b839e3d42cd0e9b1aa922b4ee83ac0811a143961e567b1421b474b1e2b89ca3' 
  AND token = '6t4IvSsg7kNwRx1Yru2gK5xaF7ir7bb/Ur9lYQ8Y48k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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