SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fbbcb492d74339446151854622bcdc00c18b0721393795629e08f22dfaedda8b' 
  AND token = 'zK94N7nXJv6u1x6kZXMDuvIZCkfc97oDud2cY3p7GJA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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