SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '518570e2e21c2dd817db2d1aec375db05c82ba579b323484fc107ee78e092e31' 
  AND token = 'MybqnSTdzHi1cxfQ2kaF/HzdPSg1q2lEWE83fzPVVoI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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