SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'da5318bdc9d140c69c64992541465b0e68db42b92fb65fa784c252d91fe704a3' 
  AND token = 'HR9+ah2gniYiMV1iwIFaNF24DrkE+Y/LrYpEV7PsJ2U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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