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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18b5b7b6eaccea7284ad1b2d2fc796cb76c86e5df21c86a1b0cd8d1a83544998' 
  AND token = 'Re5yAtDZRW24ZmCL6sg0EoYfY8gmMmYEAnLKsvGf5tM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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