SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e7b7ed99b303465020d8f0333aabea2c75e2b5bf1eb8e581b4dc321c5d8fe422' 
  AND token = 'kb9uC2iIEqcQzDCcyCDh2lXqML/z6oCKMP5u2ZySEQY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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