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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6ee7feccd4eb67b65e95f59ab1042493aeee28f756cc0ba62152768376e510d1' 
  AND token = 'AoIHtnE7VhyOt0aB72SBJUQrYxywTLmlpm++r2xdYz4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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