SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d206ee25d00d943228b08a9e5f69f4e7508707bf58fb468cded1cb337be2bf1' 
  AND token = 'N+1XxSDVfAaJ1588a3KkfhTrRZR8j4nN1XwWQFhR7Lk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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