SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8855dd4f67be981260cdf2cd23f7f2c61e4d3a78d7e27d696b506430719bc61' 
  AND token = 'HGgQ1Trol7h+wz7FrZSRcvC5ps4dniRQsXFECEAE6Nc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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