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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c78c55234f49812e85d4478d9a117f101da0431cdbfd46d6b7f5fe4f55a22b1b' 
  AND token = 'xUS+1KEWMyrNvBcCNQMb6D3Ds0HCpS/zt+NRhU1Wj+o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00066

JSON explain

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