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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50b8934807ae049601837b84afe07d2869740a498907d6be451c36e53769abaa' 
  AND token = 'R4gNUXVljSo5XBmZI0yjnRr1eJpIjjmJdTrZdZZYFi8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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