SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '474a1281295cc589c773a72846b862e0e0b75a2f0240d0ad276a6e81661fab29' 
  AND token = 'nGrPiMiYllEaYUk31VTY67gxVdLp9hc6wuWriZ302fk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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