SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7fd5290eb1c41eaa4a81f57ebfb2744ec9319767182dc2902d440695dfae5bc4' 
  AND token = 'Z/Cu/k0vZ6YQCjY/g1dEJloqaJ4hQ2wObsINKGRZWc0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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