SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '86f9a9f5bee10e1a7cb9d47f29021d77f64c00d60b44f0401753492cfd4418e9' 
  AND token = 'oxmVqpvou7Fawc6Shbo+dR8e7nwwiAMwVpmCMNRlsMQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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