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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd20dbf19125ddfd1bb5109b25e7ebe28c43d5fb3db70ab2d49419b0e562e4443' 
  AND token = 'nBS2iBQvhCumHLkiJD8/pghrrXFSKRV18B5f8aoHk2o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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