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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a8db9a1a6f49cfe1283553974df2c98d267c3336fea06b2ced3c7f5b09b1daa8' 
  AND token = 'Jjrh2zfooj5+j+Zsrkr6TkuhXiyWT0MpNHLt6cqEtCE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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