SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39ff509ff75311db844d20ec9c56ba721e6f978f41350fa44e21a684f7b687ab' 
  AND token = 'nQJ2rjkJyLuMfK6YwfUvyCFIKDuLYMBO6LDEwAlOFMs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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