SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '834656bc5eb8f7f7da09de9b802bb465a80624d51043a0b706814f0f61b1af2a' 
  AND token = 'ekIhbcZseiegoljlSfQB7Y22m0asCtfSw7GymNMbXb0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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