SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0dace9ef0c82ea5082db1b365c6fda8e1dac24ffa5c739d3e5500516accdb661' 
  AND token = 'iQqtLDuagH5vCISVC65cl8RCwD4t053pmylr+jklTrE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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