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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '548cb6ea0c536f565dfe35da6c77d8d9128d674cd98e3582c695586ca3771f9b' 
  AND token = '2RbtaZuS6w/qmWvro/gmdqc+Az/NmGgPdMicZ2GtCtE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}