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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '664b86e16e060057f82b5558d6b91cd687a872b9b71590619c5495083a8056f2' 
  AND token = 'lCaXCpattPLmB5KR1BivpxSKvxIEI6/td+SJdUXMgvs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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