SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c13b5e3b3879cd2004f67649874a2d9f61b3862791f5a4522bf6adabc16607e9' 
  AND token = 'j1Mfmw/RsxoL0FlzQDM5nFOTWhScqAHgFLGt9mNFnJ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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