SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '771c99a0c4946a769750cbcd391489777bec40adf26df6a4b6583a82c387303b' 
  AND token = 'alS+kFFsL6Kvxi7GCmHQ2WWLWtTOCIVCEHzbSMouGX4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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