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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a4fec70dc4a5be47b7771ff9221bd2eb8f638eb9b93b871d5cd88b2e53d7b18a' 
  AND token = 'au6CqqR570cSZ///oP8ProdbyZdeRpXpVDTDPpvyfZM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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