SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '743e54dfbc9c127d6eb068ba0d369838124ab864c91550e7d2e43bbdcac92532' 
  AND token = 'qOLghiOTLmh/1+j7sGXNVvvd4pdwCfV060sedxTVumg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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