SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '142cb209ab97ec2236b79c08c675953279509c5bc96329ea54dd97d6b62c95cc' 
  AND token = '7Zey7puOflUfppi/QutF6JEYCJ66hS93hG3iNn92eLY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}