SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ffd507796d6497aa4c3280d958590073291ff763f800aea679fc1265da6329c5' 
  AND token = 'rI+8EEm0pzrBOyn3pLsFfASzWNId+sOCWvxnWGUWFGY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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