SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6b100cc469966cb1fd6c04224f57399f756249594ed3a2941a8d1683fb7a5fe' 
  AND token = 'trAu4SaVTFcjXgsWa50Tz1fKZmEPN+RT0K1TXfkNRBI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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