SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8635aecc06627cc8685dc4f9662836e377ed415fda2edbccd452a27fae7aa563' 
  AND token = 'mbS2hD/u8mBMbuTY1DgnnLo8ZR+pEU3tVNFLlAwTSxw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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