SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8e353754076f825e67e488f82f3c15bd6ca82fafa3d1af1c086cf493d2cd41b' 
  AND token = 'U+KobzPg0qqfs41duau+RBpB/tV1XVo+THA9KwetmhY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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