SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3178c755a37b6e11c0474395db0b9e2876347e18672ba4a86aa4a63481dd4400' 
  AND token = 'JtAT0TAEstX1+n+RLNd0oYsrdLW874pDQ5ETiHZrzJo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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