SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81c63da1e44513e9373be518acb709ad3a513b57b4ed37a7ec863c17f3e582fa' 
  AND token = 'AdpHTDtSymJog4usVHtbCJANBEAjYjm61QvK7pakiJU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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