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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '34571c7d1b950420343d8ff644b7a49cf5fb5c88398cd6ecb2c9516417b69b0c' 
  AND token = 'KbUmnWus1zS++ZMJFb2lzsUAXKfN77JkPpa4YnsdRt0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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