SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5470b916c2b0d4b59d0b866abec22e85adf2cc08f4a26314d47aaaf72fb1f49c' 
  AND token = 'fFmGVuIxmcBeFvucLEjhM8lAi9rZjtgxDDi/QucYNKM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}