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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e1a4311f0cf4083c9bf34e8ba6edad87c8b557c516a0cf7e3e07de6d1cb69e37' 
  AND token = 'RQG6HTBt+EwBRpfAS3f53MljKZzwcIXxhEBHkKt8csM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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