SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c10e7f1941bd604180b337df1e19733d4ffe342c2e72528a37548886ae0fab6' 
  AND token = 'oSg1ZbbknB5mpXfKHIUIUjiPZDi0dKpcovCTaFr+LDs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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