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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ddf83306bebb7b5e117b8d8317bac5cc65e1d812d958b6e66008d1f6efc3dd3a' 
  AND token = 'yhcJDXlcPWPZGLiGUx1Vs9wCKK5SJrpqCzBgokSIazc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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