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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7c994c9a0f51856b3df4a390047e873dfa09062bdf4be9e79b8e658daad999f1' 
  AND token = 'HMq1OKepgS6pbk1kg3KXAPc56B/61JwX7UtW3X9rqTA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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