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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e6e4286f12522ee8791dd5e409ef295cd2f81e57dd476f05c56fb4341f2810a7' 
  AND token = 'wRU1cBHB9Kn9nFtKuCKRyc0D3eZd/p02mXM8AZ+IqaQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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