SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e77abf8d5fc9279f966c4492549da7ca316e9519a4df7bdfe55f1085596ec337' 
  AND token = 'rvJ0C2KL4RlnjOSCgbPpZ1bP2+ZXRg/uURknkGgE1mA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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