SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f1f36edae7f8a4d22c8b95dab02d84add2d10c981d4ee307924d568ed1d7f184' 
  AND token = 'sx3NFaszY1cygD+LzKTeD42ClAFPINVFrKp6xBW6ANY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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