SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f220bdaad91188909bde18d0a71f64357d354105b509ae1799f13f71be722355' 
  AND token = 'mmcYNGOo2VzJNgrLeMj3WTZ3GXtqQxFEAT3RdiH9tow=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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