SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a1ddef849ad8d554b8d001d970231e4495f6dc9d82be547f9024008c61aaeee1' 
  AND token = 'lO8leJh0waXHyOnFEMTyZhLJtBdci0LHAURWTNevQP4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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