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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a56b0e39fdcb056364b79043b775199ec324fd6bdeca197ae7be8d2f98a81b40' 
  AND token = 'sSfllAPjc4Uq0IHwmyidY4FhWo6AN9tnMnSOg20g4SY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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