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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6135a6f3362364e4d998dd0ef1b89a0aa85d3e1e34ca5a32f36894628ab1e444' 
  AND token = 'cwpl/i7dDOqAk+eC4mvlUFPtuTkKPQN0UYR29FqKgAs=' 
  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"
    }
  }
}