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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c263f177718e9d20064d8323a268bd4a1b381fd052a87755c05fb0bcf0f1cd94' 
  AND token = 'IUcm2WP8Bw0TUZYHWUBqIE4nNg+ZB2iW3WESIkLUmhw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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