SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df8fa289c80beca12e572ea967e598a1d12e84db1efa28979883c4e47f05360a' 
  AND token = 'o+XFQZCltA+GZQTFcygqs++qVHJmbhMMRGDZZwDP9po=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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