SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5920404cb91cff5036b5cbbaf145d53f9cf0853956897419f2fda8d4f5418a0c' 
  AND token = 'ymRJwxkZU50YvBZyTO2jIz+CzWGgA7ro6ELz4wXisOY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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