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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '532d5766a4c928b425ba3bf8d9b7c08a1e990b13ea5d4e74ef992d8a0a71d978' 
  AND token = 'HcytesQ7AvmDrFAXbqMzernYqz5VFIEfzzOvP67StYM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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