SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8c3db72b93ee323d6791569852e704634591d974232eed97b7ac6cbf95f0557' 
  AND token = 'qO3VWCMYZoFJo5aLycqcg47P1N2KffXFt5VzlixpquQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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