SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8469e1533315da4a040669ba3cc8b18f4dca921827c7a7e211ceff397da4a5c' 
  AND token = 'NBa37fUhdZWJdRs4FhEfrzBG2JqZK8Q+C0+nuZnHgN0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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