SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38c6ad3c841dc1af125dfdcb4661b994c60be833adc7f7e0468d2eb76dd4dd4e' 
  AND token = 'VWN9M2u6c/cUpR4XgEkirQAIwvmjmxHa+1dYlYObtCY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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