SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '63438e083e144513a01e69252341f8e576ae4e34038572f56bf92d31c42900f0' 
  AND token = 'ZSjF4Xw9/gtA/IzF5WU8s5ywpFuNhqrlVPGjsfKJTXA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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