SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f42c067e20d32cea2ee9c1cb64dd3aa362aa936a51517da78bd05d5280e1f545' 
  AND token = '2LdwS88ZTVsGMeTkZ3glPrHPgfUONUNwJAuRzEQb/AI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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