SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5412256556fe083c29f876648877de2776f0be0f0dee15f354066b9cc879c1b' 
  AND token = 'KWe3mrWN11nIFTSBCAN/o1hnro6ZtoFMfUNhATLsoUc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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