SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a61c1be929ddfde84baf4adfd2b34517fbada3034ea3d383baa0ed62463da26' 
  AND token = 'OFgmQpKdVcNDI9UxROADA+HF87BGEei+SHKpEj3cx7g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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