SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4cd5b67ee6f5b8e51a6e815ac4d3439706af1b4080662cb9d9664051547b22d4' 
  AND token = 'aZFc/+5fnB88KiaCn+jGzYH8wNsxvo3dLZ3oqsjuZAQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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