SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb20f2c4b4d5a844a70a6ac8600ba7d9dc67da9793f88f69a368fb492ed577e1' 
  AND token = 'RZdTXk/iq0Ff10ebzdr4tpDd42DjjRYHUrSOWQUzLrg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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