SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ffe0915045dbd593419fdb5510c9a33cd596629b735dd8c156dd82fa0f854a21' 
  AND token = 'kUpLTwJjFE5+3IZ+6eIpOd8MEsD+Bx+OOb5I4v4WMuk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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