SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9601461988a00b292b7709ab083568cef0e57dfb712753627971f6d6e0fc3837' 
  AND token = '2OyDw4jK/nrZgcVKuvDDQ/3lr47INFsgsAYD8lUTqvI=' 
  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"
    }
  }
}