SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7a3213a292f0b75227fe8eef0b6062152814dac7696ac46def13355b9125004' 
  AND token = '8uBSRiMc9svnemzp/V/7Suw+HjgDD4XgMfPPldvqB1s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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