SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92100812e1e23779bb950b09d6755770ab66f2195f1f0447e578ef35fc914a60' 
  AND token = 'mhVFP7jAnU0nt5SNufxgAaTO0+pMnvFotHQIUQ3yMas=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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