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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d695b1b022f6d20895130f4c6f53f62d41d6c49fd954f99a0e3fb96aca4a3a9' 
  AND token = 'UGw3Lyy/5vYrPk37M7+tHgj6TIbHdWq5XZIse/DrN2o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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