SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bbf6c6f914656851b80e11b7842cd758b9644ce7e8096a286e59cff4dbc2d752' 
  AND token = 'Plv0hxRkxAYaz5nd0rOiGV44FEGmyZsigy6Dbxp1s+Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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