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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '766e17acedbe0ab461c2d265f7b5da9ec392696a98a0a6f0ce570735e4370e66' 
  AND token = 'Qd1+8Z5AqCbdKpJwAAfepK6OSPVLH0yiRgazTa/jc8g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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