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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8dfa798f4b54f910a75ab10097c544b273acfd46ee6e631ec678a53e7c9ef36' 
  AND token = 'GexCwlh8B7Wt0G+vdZyaUMucAuxgUmsBbMI53CZFJW4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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