SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e2a5781969a78fc1d8e0b502d1d6133af0b0b666c27be767860f0bcc4d2fa84' 
  AND token = '+J9tgxZzXaZVoNb/h+ftXSfF+HMVE/EKOBNfrgxHPlw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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