SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '327284ec0a0df3085cdbfffc878e3219d1f28083ef3305a76af4cc135ecd3f46' 
  AND token = 'dVOcMOtb23fQvr8HOMhOVBn5iHiIioSJPonUVyGjMfk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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