SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6791682b33576e55fec42b4eee8d2998df92450b10028fe3e06019e0ee9f73c3' 
  AND token = 'lNPda1b1zsUZKge0eHsjnJ5kzoAZLROPNT1HXDev/Iw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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