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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b21eb16c5dc798f2a61b97e281f86088b80dc99bb4aad579bb866f7857a8f3d4' 
  AND token = 'pRCLWJ3rTdafJZ8Ry5Wwcah0Vb8S7UTERAUrMClkoJ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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