SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '65e7862aabf3ea3b62af91520b14496d4a6878b87d3005a2f9f303d8aadab818' 
  AND token = 'EbF+/+khOCKM+ccqK0CabA1BvCJrl6tVj2Ckq5/ZsQ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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