SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c3208b564444ca0018693157b0456176b592e7d7db3ff29b83fa48d7f1f8f2b' 
  AND token = 'qfQKAQKN1gh+mHfIG5I38CuPX1fxRIHBkJ07egR/JIw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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