SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6429516cd5acdbe869d983b029a8f0ab5f81029e9cc36afed7db45e347325179' 
  AND token = 'hVOvyiBllwe79bbIXCIc1gDAqcTLp+f+IkO88bhaF54=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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