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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c10edc6b4f3b061d3714305e65e9a656e8c84e23be92cdd36d319540c9ca0f43' 
  AND token = '8e55aJXGSrRlHqfjfaeYYZuZYY6kbK6Wh+aKyaRZKCQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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