SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f1cd2821bf1af114110629c24ed0b1126eca88a91546b14beaca6243011c70f' 
  AND token = 'ukWTDhdBcdQCESpvAm15/QKtiBbkMnq7+TWoNEv+NZ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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