SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '819d8d13a99b419efbcba79bbda019fc76cd0e1046675c4989671fb1cdbb3f03' 
  AND token = 'CPBKRHkRoHlS+gOYVfU9VYs24+wZN8WaRJU7QfIbwmQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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