SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b39a66bceac576084337e5e29cb7f8cc614c56fcea618bac70bbe4ec914b51f' 
  AND token = 'HKrE7vzCM4lz3hgZFTK5fkY4oex7uczKHkVf+Btb/x0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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